Python 3 Programming Tutorial - Sockets: client server system

Key Takeaways

hello everybody and welcome to another Python tutorial video on sockets so up to this point we've talked about how we can use sockets to attempt to make connections uh but we haven't really talked too much about sending and receiving data on both ends so what I'd like to cover in this video is going to be um both making a client coding in the acceptance of uh receiving data as well as sending data from a client so one of the easier things that we can do here or more I saying things that we can do um is to create some sort of client where we can make a connection um type some stuff into that you know connection that we've made via telet so we can type in some data from the client send that data to the server which will receive that data digest that data and then maybe you know send out some sort of response um back to the client so in our case we're just going to make it really simple but you can Envision U more advanced things that you could do with the data once you received it um the other thing that we want to do is we want to if it's a server the server needs to be able to accept requests right and connections and all of this needs to be able to accept data and send back data um specifically to the connection um in question so there might be 15 people browsing a website but you see exactly what you're doing you don't like click on it you know go to a website and then start being moved around because of what other people are doing normally anyway um no you do your own thing on that website you view your whatever Pages you wanted to click and so the same thing here if you're going to create some sort of a server so to speak you're going to want to serve each connection specifically um the only um thing that comes to mind right away that is not the case there is like if you're creating some sort of like chat room where everything someone types uh is viewable to every else you know something like that but anyway uh moving right along uh let's go ahead and get started so uh with the code that we have so far we're actually going to leave everything that we've made the only thing I will change uh for now is we're just going to comment out this connection address part and then the connection information that we print out and now we're ready to actually start handling this stuff and even though it might sound very deep and confusing it's actually going to be pretty basic uh and we'll be able to cover all of this within this this single video so first we're going to want to do Define um so you've got a server and a client right so we're going to define the uh client or we're going to Define threaded uncore client and uh the parameter for threaded client will be connection CN and uh we'll do um connection. send and again uh to stress the difference of python 2 and 3 Python 3 makes the distinction between like bite strings and strings uh whereas python 2 does not so if you're if you're doing this tutorial in Python 2 you would not need to do encoding and decoding you would just do the natural thing but Python 3 makes a distinction and and rightfully so um so we have to do encoding and decoding so basically everything we send out we're going to need to encode everything we receive we're going to need to decode but even on messages that receive you have to decode them do whatever you want then encode and send them back so when we do con. send we're going to need to do send St for string. ncode and then we're just going to say a message like welcome uh type your info okay and that's just going to send an in uh you know kind of like an informal greeting to the person also it won't naturally make a new line so we're going to naturally make a new line with back sln or at least it may not at some it it probably will anyway moving on um now we want to make a loop that will basically continue sending the information so if you remember before as soon as we made our connection boom connection dropped so actually we want to go ahead and and keep that thread alive um instead of dropping as soon as we get a connection so we're going to go ahead and say w true for to make our little infinite Loop here and then data equals con. racv and then at what buffer rate basically 2048 okay so that's the data and then we're going to say our reply so data is anything that we receive a reply is going to be equal to um and actually we'll just make the reply uh something basic like server output colon and then um plus data. decode um and you want to decode it tf8 so again all the data that we received we have to decode and then the reply is server output plus data. Z code uh in utf8 then um what we're going to do is if not data break so we can actually stop this connection and then we're going to do connect con. sendall string. ncode reply so here's a perfect example where we've accepted data we've had to decode it we've made our changes and then we've done um an end code to to send it back so condet send all encode the reply and then once uh this wild true Loop is completed while you know we're not have with the connection is not there anymore we're going to go ahead and do condu close and that's basically it for a threaded client we don't have to really do anything else there so now what I want to go ahead and do is again we'll come down here and we'll just say wow true and we'll take the same stuff that we had before here so we'll just tab this over uncomment it so now we're printing the connection and then um we're going to start this uh thread basically um so we're going to use well we haven't imported it have we so we're going to come back we're going to come up to the top and we're going to go from underscore uh thread actually lowercase thread import everything and then we'll come all the way down here and now we will import or we're going to do um start new thread so startor newcore thread and then we're going to start a thread with the threaded client okay so we'll copy that paste and then even though there's only one parameter here by just absolute default it must be a tle so that's just the way it is don't ask questions and it's going to be con comma nothing okay you just don't put anything there it requires a tupal so we make a tupal just you just have to please the python Gods here um and that's it okay so now what we're doing is each time someone makes a connection it's going to pass them through threaded client it's going to give them their own thread entirely it's fancy stuff now um we'll go ahead and run this and just see if we had any errors so save and [Music] run I don't see it popping up yet where are you there we are okay so I think that we've started um we probably should put something here like I don't know print waiting for a connection or something I don't know just something so we know that we're at a point where we want to be but we'll leave it up for now and now I'm going to bring over lovely Raspberry Pi and Raspberry Pi is going to connect for us now I've already forgotten what port we are on I think it's 5555 right yes okay so Raspberry Pi is going to use tnet again if you don't have telnet on Linux you would need to do you know P sudo app to get install tet yay but I already have it so I don't need to do that so we're going to do tnet and then now you need to use your your IP now I'm going to be using my local IP so 192 1682 and I believe it's eight from 28 interesting anyway um oh that makes sense I suppose because we we're in SSH so anyway um port five five five five uh we'll hit enter and we are connected here is our server that's running at the moment and it indeed says hey you've been you're connected to uh 192 168 216 so we have a valid connection currently and now we could say something like I don't know hello enter and then we see that uh the server received our hello it was able to decode our hello our fancy Dancy hello and it adds server output hello right back to us so that's cool okay so obviously this is very basic um this output that we're receiving is it's just saying it's a server output plus whatever we sent in but you can imagine uh think you might be doing something with this data um you could also be sending instructions uh the thread you know the client you know decodes your instructions it does the things it needs to do and it sends back some information and the server says yeah you did a good job here's some more instructions and so on so that's generally what we're going to be using this the sort of thing for um but here you go you've got uh good server and client communication happening right before your eyes so anyways um I think that covers the basics of sockets pretty darn well um so that's going to be the final video in these at least Basics to sockets we might come back and really rehit sockets just as we've kind of rehashed over threading shown some more examples um and all that if anybody has any specific uh aspect of sockets that they'd really like to see uh feel free to make a suggestion and chances are I'll make a video on it um if anybody has any questions or comments on this topic please feel free to leave them below uh as always thanks for watching thanks for all the support and subscriptions and until next time